Continuation of research intended to lead to the total synthesis of the macrolide antibiotics methymycin and boromycin is proposed. An approach to the C(1)-C(8) segment of the aglycone methynolide is being pursued, in which the complete carbon skeleton is assembled at the first step. Two of the four necessary asymmetric centers are in place, one center requires a stereoinversion, and a fourth is to be developed at the next stage. Additional functional group manipulation will be carried out to transform the cycloheptanone precursor to an intermediate suitable for aldol condensation with a previously synthesized aldehyde, corresponding to C(9)-C(11) of methynolide. Attachment of the desosamine residue will then complete the total synthesis of methymycin. Further development of the synthesis of boromycin will also be pursued. The initial phase of work on this macrolide has led to the preparation of a C(3)-C(12) segment in the "southern half". Elongation of this linear segment by chain extension from functionality at each terminus is contemplated, thus completing one half of the boromycin macrocycle.